The adaptive coding and modulation ACM (Adaptive Coding and Modulation) technology is a transmission technology having a channel-adaptive feature and is established on the basis of channel estimation. Availability of an air interface link is estimated in real time by using a detection mechanism of a receiving end, and an indication for switching a modulation and coding scheme is automatically generated; and then, the switching indication is fed back to a sending end through a feedback channel, and the sending end automatically changes the modulation and coding scheme of a service according to the switching indication, thus realizing a tradeoff between system capacity and anti-interference capability of a system, maximizing overall transmission performance of the system, and achieving an objective of efficient and reliable transmission.
As shown in FIG. 1A and FIG. 1B, a conventional method for transmitting service information is provided. In the method for transmitting service information, a same adaptive coding and modulation profile table (ACM profile table) needs to be configured for the sending end and the receiving end. The ACM profile table includes multiple (such as 16) ACM profile identifiers (profile IDs). Each profile ID corresponds to a modulation and coding scheme, and different modulation and coding schemes correspond to different transmission reliability and transmission efficiency.
It can be known from FIG. 1A and FIG. 1B that, when ACM information is transmitted between the sending end and the receiving end, in order to save bandwidth, generally only a profile ID (such as profile ID 0) is transmitted. In this way, first service information to be sent is modulated and coded at the sending end according to a modulation and coding scheme corresponding to a profile ID in the ACM profile table, and then, the modulated and coded service information is sent to the receiving end together with the profile ID information. At the receiving end, the profile ID information is extracted, and a corresponding modulation and coding scheme is searched in the ACM profile table according to the profile ID, and finally, the service information is demodulated and decoded according to the modulation and coding scheme, thus obtaining needed service information.
However, in the procedure of implementing the foregoing process, the inventor finds that the prior art has at least the following problems:
Because the sending end and the receiving end use the same ACM profile table, if the ACM profile table of the sending end and the ACM profile table of the receiving end need to be updated, the ACM profile table of the sending end and the ACM profile table of the receiving end need to be switched strictly synchronously to ensure that the service in transmission is not interrupted. Otherwise, when the ACM profile table at the sending end is switched while the ACM profile table at the receiving end remains unchanged, because modulation and coding schemes corresponding to a same profile ID in the ACM profile tables may be different, the receiving end cannot demodulate and decode the service information, thus causing an interruption of the service.